The present invention relates to a method for the monitoring of suspensions, liquid emulsions, mixtures and the like to determine if change in relative component concentration has occurred therein. It is particularly applicable to the monitoring of coal-aqueous slurries to determine if coal settlement has taken place in such slurries.
It is important that certain characteristics of liquids, suspensions and the like be monitored for various purposes. For that reason certain monitoring methods and apparatus by which monitoring can be effected heretofore have been developed. For example, U.S. Pat. No. 4,041,502 describes measuring sedimentation in blood samples by passing light wave energy through a glass tube enclosed column of the sample and recording that signal in such manner as to provide a plot of the changing location within the sample of the separation boundary between blood cells and clear plasma fluid. U.S. Pat. No. 4,442,700 uses ultrasonic wave pulsing through the casing of a lead-acid battery to determine specific quantity (density) of the electrolyte therein and hence indication of the serviceability of the battery. U.S. Pat. Nos. 3,028,749 and 3,911,726 also describe ultrasonic procedures for determining various parameters, e.g., density, of liquids as does U.S. Pat. No. 4,235,099 which relates to a method and apparatus particularly useful for liquids specific gravity mensuration in medical and related activities. U.S. Pat. No. 4,007,319 describes use of electrical conductance for monitoring a suspension polymerization reaction so as to anticipate for corrective counteraction thereto, of the onset of reaction conditions that signal incipient failure of suspension formation.
Other patents which deal with aspects of product monitoring as related to density, sedimentation and analogous considerations include U.S. Pat. Nos. 2,668,365; 2,715,831; 2,825,698; 2,978,899; 3,514,217; 3,529,153; 3,896,660; 3,964,037; 4,007,315; 4,002,053; 4,041,500; 4,047,891; 4,048,844; 4,140,007; 4,261,196; 4,297,608; 4,466,272; 4,487,278; 4,506,541 and 4,527,420.
Those skilled in the art readily understand the wide range of potential applications for suspension, emulsion and mixture monitoring in various industries such as food, pharmaceuticals, minerals processing, waste treatment, paper, etc. Another area of special applicability for such monitoring is in respect to coal fuels wherein the ready facility for monitoring coal slurries used, e.g., for fuel purposes is desirable so that determination of optimized thickener and surfactant amounts to be added to a fuel slurry at production thereof to insure long term stability, are ascertainable. U.S. Pat. No. 4,441,889 describes a coal-in-aqueous slurry form wherein additive materials such as surfactants, stabilizing agents, thickeners, etc., are employed to disperse and stabilize the coal to high solids concentrations of 70% by weight, or higher. These mixtures are free-flowing, have excellent long term storage stability and being in fluid form, can be burned in apparatus normally used for burning fuel oil. Since these coal-aqueous slurries generally will be stored for some time prior to use for their intended purposes any sedimentation which might occur therein would be undesirable when the mixture was later used in a fuel burning operation such as in a boiler. By monitoring over a period of time representative samples of the slurries taken from production runs, the long term stability of the slurries are learned as is data useful for compensating in future production for any instability noted in monitored prior produced coal-aqueous slurries of given coal solids concentration.
It is therefore desirable that a highly effective, yet simple method be provided for monitoring the solids concentration of coal-aqueous slurries and the like and by non-destructive procedure and under the natural conditions which such slurries subsist from time of production until ultimate end use thereof.